1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * This file is available under and governed by the GNU General Public
27 * License version 2 only, as published by the Free Software Foundation.
28 * However, the following notice accompanied the original version of this
29 * file and, per its terms, should not be removed:
30 *
31 * Copyright (c) 2004 World Wide Web Consortium,
32 *
33 * (Massachusetts Institute of Technology, European Research Consortium for
34 * Informatics and Mathematics, Keio University). All Rights Reserved. This
35 * work is distributed under the W3C(r) Software License [1] in the hope that
36 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
37 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
38 *
39 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
40 */
41
42
43 package org.w3c.dom.bootstrap;
44
45 import java.io.BufferedReader;
46 import java.io.InputStream;
47 import java.io.InputStreamReader;
48 import java.lang.reflect.InvocationTargetException;
49 import java.security.AccessController;
50 import java.security.PrivilegedAction;
51 import java.util.ArrayList;
52 import java.util.List;
53 import java.util.StringTokenizer;
54 import org.w3c.dom.DOMImplementation;
55 import org.w3c.dom.DOMImplementationList;
56 import org.w3c.dom.DOMImplementationSource;
57
58 /**
59 * A factory that enables applications to obtain instances of
60 * <code>DOMImplementation</code>.
61 *
62 * <p>
63 * Example:
64 * </p>
65 *
66 * <pre class='example'>
67 * // get an instance of the DOMImplementation registry
68 * DOMImplementationRegistry registry =
69 * DOMImplementationRegistry.newInstance();
70 * // get a DOM implementation the Level 3 XML module
71 * DOMImplementation domImpl =
72 * registry.getDOMImplementation("XML 3.0");
73 * </pre>
74 *
75 * <p>
76 * This provides an application with an implementation-independent starting
77 * point. DOM implementations may modify this class to meet new security
78 * standards or to provide *additional* fallbacks for the list of
79 * DOMImplementationSources.
80 * </p>
81 *
82 * @see DOMImplementation
83 * @see DOMImplementationSource
84 * @since 1.5, DOM Level 3
85 */
86 public final class DOMImplementationRegistry {
87 /**
88 * The system property to specify the
89 * DOMImplementationSource class names.
90 */
91 public static final String PROPERTY =
92 "org.w3c.dom.DOMImplementationSourceList";
93
94 /**
95 * Default columns per line.
96 */
97 private static final int DEFAULT_LINE_LENGTH = 80;
98
99 /**
100 * The list of DOMImplementationSources.
101 */
102 private List<DOMImplementationSource> sources;
103
104 /**
105 * Default class name.
106 */
107 private static final String FALLBACK_CLASS =
108 "com.sun.org.apache.xerces.internal.dom.DOMXSImplementationSourceImpl";
109 private static final String DEFAULT_PACKAGE =
110 "com.sun.org.apache.xerces.internal.dom";
111 /**
112 * Private constructor.
113 * @param srcs List of DOMImplementationSources
114 */
115 private DOMImplementationRegistry(final List<DOMImplementationSource> srcs) {
116 sources = srcs;
117 }
118
119 /**
120 * Obtain a new instance of a <code>DOMImplementationRegistry</code>.
121 *
122
123 * The <code>DOMImplementationRegistry</code> is initialized by the
124 * application or the implementation, depending on the context, by
125 * first checking the value of the Java system property
126 * <code>org.w3c.dom.DOMImplementationSourceList</code> and
127 * the service provider whose contents are at
128 * "<code>META_INF/services/org.w3c.dom.DOMImplementationSourceList</code>".
129 * The value of this property is a white-space separated list of
130 * names of availables classes implementing the
131 * <code>DOMImplementationSource</code> interface. Each class listed
132 * in the class name list is instantiated and any exceptions
133 * encountered are thrown to the application.
134 *
135 * @return an initialized instance of DOMImplementationRegistry
136 * @throws ClassNotFoundException
137 * If any specified class can not be found
138 * @throws InstantiationException
139 * If any specified class is an interface or abstract class
140 * @throws IllegalAccessException
141 * If the default constructor of a specified class is not accessible
142 * @throws ClassCastException
143 * If any specified class does not implement
144 * <code>DOMImplementationSource</code>
145 */
146 public static DOMImplementationRegistry newInstance()
147 throws
148 ClassNotFoundException,
149 InstantiationException,
150 IllegalAccessException,
151 ClassCastException {
152 List<DOMImplementationSource> sources = new ArrayList<>();
153
154 ClassLoader classLoader = getClassLoader();
155 // fetch system property:
156 String p = getSystemProperty(PROPERTY);
157
158 //
159 // if property is not specified then use contents of
160 // META_INF/org.w3c.dom.DOMImplementationSourceList from classpath
161 if (p == null) {
162 p = getServiceValue(classLoader);
163 }
164 if (p == null) {
165 //
166 // DOM Implementations can modify here to add *additional* fallback
167 // mechanisms to access a list of default DOMImplementationSources.
168 //fall back to JAXP implementation class DOMXSImplementationSourceImpl
169 p = FALLBACK_CLASS;
170 }
171 if (p != null) {
172 StringTokenizer st = new StringTokenizer(p);
173 while (st.hasMoreTokens()) {
174 String sourceName = st.nextToken();
175 // make sure we have access to restricted packages
176 boolean internal = false;
177 if (System.getSecurityManager() != null) {
178 if (sourceName != null && sourceName.startsWith(DEFAULT_PACKAGE)) {
179 internal = true;
180 }
181 }
182 Class<?> sourceClass = null;
183 if (classLoader != null && !internal) {
184 sourceClass = classLoader.loadClass(sourceName);
185 } else {
186 sourceClass = Class.forName(sourceName);
187 }
188 try {
189 DOMImplementationSource source =
190 (DOMImplementationSource) sourceClass.getConstructor().newInstance();
191 sources.add(source);
192 } catch (NoSuchMethodException | InvocationTargetException e) {
193 throw new InstantiationException(e.getMessage());
194 }
195 }
196 }
197 return new DOMImplementationRegistry(sources);
198 }
199
200 /**
201 * Return the first implementation that has the desired
202 * features, or <code>null</code> if none is found.
203 *
204 * @param features
205 * A string that specifies which features are required. This is
206 * a space separated list in which each feature is specified by
207 * its name optionally followed by a space and a version number.
208 * This is something like: "XML 1.0 Traversal +Events 2.0"
209 * @return An implementation that has the desired features,
210 * or <code>null</code> if none found.
211 */
212 public DOMImplementation getDOMImplementation(final String features) {
213 int size = sources.size();
214 String name = null;
215 for (int i = 0; i < size; i++) {
216 DOMImplementationSource source =
217 (DOMImplementationSource) sources.get(i);
218 DOMImplementation impl = source.getDOMImplementation(features);
219 if (impl != null) {
220 return impl;
221 }
222 }
223 return null;
224 }
225
226 /**
227 * Return a list of implementations that support the
228 * desired features.
229 *
230 * @param features
231 * A string that specifies which features are required. This is
232 * a space separated list in which each feature is specified by
233 * its name optionally followed by a space and a version number.
234 * This is something like: "XML 1.0 Traversal +Events 2.0"
235 * @return A list of DOMImplementations that support the desired features.
236 */
237 public DOMImplementationList getDOMImplementationList(final String features) {
238 final List<DOMImplementation> implementations = new ArrayList<>();
239 int size = sources.size();
240 for (int i = 0; i < size; i++) {
241 DOMImplementationSource source =
242 (DOMImplementationSource) sources.get(i);
243 DOMImplementationList impls =
244 source.getDOMImplementationList(features);
245 for (int j = 0; j < impls.getLength(); j++) {
246 DOMImplementation impl = impls.item(j);
247 implementations.add(impl);
248 }
249 }
250 return new DOMImplementationList() {
251 public DOMImplementation item(final int index) {
252 if (index >= 0 && index < implementations.size()) {
253 try {
254 return (DOMImplementation)
255 implementations.get(index);
256 } catch (IndexOutOfBoundsException e) {
257 return null;
258 }
259 }
260 return null;
261 }
262
263 public int getLength() {
264 return implementations.size();
265 }
266 };
267 }
268
269 /**
270 * Register an implementation.
271 *
272 * @param s The source to be registered, may not be <code>null</code>
273 */
274 public void addSource(final DOMImplementationSource s) {
275 if (s == null) {
276 throw new NullPointerException();
277 }
278 if (!sources.contains(s)) {
279 sources.add(s);
280 }
281 }
282
283 /**
284 *
285 * Gets a class loader.
286 *
287 * @return A class loader, possibly <code>null</code>
288 */
289 private static ClassLoader getClassLoader() {
290 try {
291 ClassLoader contextClassLoader = getContextClassLoader();
292
293 if (contextClassLoader != null) {
294 return contextClassLoader;
295 }
296 } catch (Exception e) {
297 // Assume that the DOM application is in a JRE 1.1, use the
298 // current ClassLoader
299 return DOMImplementationRegistry.class.getClassLoader();
300 }
301 return DOMImplementationRegistry.class.getClassLoader();
302 }
303
304 /**
305 * This method attempts to return the first line of the resource
306 * META_INF/services/org.w3c.dom.DOMImplementationSourceList
307 * from the provided ClassLoader.
308 *
309 * @param classLoader classLoader, may not be <code>null</code>.
310 * @return first line of resource, or <code>null</code>
311 */
312 private static String getServiceValue(final ClassLoader classLoader) {
313 String serviceId = "META-INF/services/" + PROPERTY;
314 // try to find services in CLASSPATH
315 try {
316 InputStream is = getResourceAsStream(classLoader, serviceId);
317
318 if (is != null) {
319 BufferedReader rd;
320 try {
321 rd =
322 new BufferedReader(new InputStreamReader(is, "UTF-8"),
323 DEFAULT_LINE_LENGTH);
324 } catch (java.io.UnsupportedEncodingException e) {
325 rd =
326 new BufferedReader(new InputStreamReader(is),
327 DEFAULT_LINE_LENGTH);
328 }
329 String serviceValue = rd.readLine();
330 rd.close();
331 if (serviceValue != null && serviceValue.length() > 0) {
332 return serviceValue;
333 }
334 }
335 } catch (Exception ex) {
336 return null;
337 }
338 return null;
339 }
340
341 /**
342 * This method returns the ContextClassLoader.
343 *
344 * @return The Context Classloader
345 */
346 private static ClassLoader getContextClassLoader() {
347 return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
348 @Override
349 public ClassLoader run() {
350 ClassLoader classLoader = null;
351 try {
352 classLoader =
353 Thread.currentThread().getContextClassLoader();
354 } catch (SecurityException ex) {
355 }
356 return classLoader;
357 }
358 });
359 }
360
361 /**
362 * This method returns the system property indicated by the specified name
363 * after checking access control privileges.
364 *
365 * @param name the name of the system property
366 * @return the system property
367 */
368 private static String getSystemProperty(final String name) {
369 return AccessController.doPrivileged(new PrivilegedAction<String>() {
370 @Override
371 public String run() {
372 return System.getProperty(name);
373 }
374 });
375 }
376
377 /**
378 * This method returns an Inputstream for the reading resource
379 * META_INF/services/org.w3c.dom.DOMImplementationSourceList after checking
380 * access control privileges.
381 *
382 * @param classLoader classLoader
383 * @param name the resource
384 * @return an Inputstream for the resource specified
385 */
386 private static InputStream getResourceAsStream(final ClassLoader classLoader,
387 final String name) {
388 return AccessController.doPrivileged(new PrivilegedAction<InputStream>() {
389 @Override
390 public InputStream run() {
391 InputStream ris;
392 if (classLoader == null) {
393 ris =
394 ClassLoader.getSystemResourceAsStream(name);
395 } else {
396 ris = classLoader.getResourceAsStream(name);
397 }
398 return ris;
399 }
400 });
401 }
402 }